People often wish to cook on their outdoor cooking grills foods, such as pizza, that are not necessarily traditionally considered grill foods. An exemplary hinged-lid grill 10 of the prior art is shown in FIGS. 1 and 2. The grill 10 is exemplary in that it includes a frame 12 supporting a lower base portion 14 to which an upper lid 16 is hingedly attached, typically toward the rearward edge of the base portion 12, by hinges 17. The base portion 14 and lid 16 cooperate to define therebetween a cooking chamber 15. The cooking chamber houses a grilling surface such as grate 20 (FIG. 2) that is supported in or on the lower base portion 14. The upper lid 16 includes a handle 18. Often, the handle is a straight, hollow metal tube supported between side portions of the upper lid 16. The handle is typically oriented toward the front of the grill in alignment with a front surface 16a of the upper lid 16, as shown in the exemplary grill of FIGS. 1 and 2.
A heat source is housed below the grate. The cooking chamber may be heated by charcoal, wood or even an electric heating element placed in the bottom of the cooking chamber, or more typical for this particular style of grill, by liquid fuel, such as natural gas or propane.
With respect to pizza, the desired cooking temperature for many pizza recipes is very high, on the order of about 600 to 750° Fahrenheit or more. It is important that the temperature within the cooking chamber be particularly consistent, both spatially (the temperature is substantially the same everywhere within the cooking chamber) and temporally (the temperature does not fluctuate significantly with time).
First, the temperature should be spatially consistent so all of the ingredients cook properly. A common problem with cooking pizza, particularly in grills, is that the crust cooks too quickly relative to the ingredients on top of the crust such that the crust becomes too dry or even burns before all of the ingredients on top of the pizza are fully cooked or properly melted. Thus, temperature uniformity as a function of height above the heating element (e.g., charcoal, wood, or flame burners) is desired. Furthermore, if the temperature is not uniform in the horizontal direction, some sections of the crust may burn before other sections of the crust are fully baked.
Even further, maintaining a consistent temperature over time also is often important to cooking pizza (as well as many other foods). First, a consistent, proper temperature will, of course, cause the food to cook faster than a fluctuating temperature and temperature fluctuations can lead to the food not cooking properly all the way through to the center.
Often, it is particularly difficult to maintain consistent temperature in conventional cooking grills for several reasons. First, in a conventional hinged-lid grill, such as many conventional gas grills, the grill must be opened (by pivoting the hinged lid upwardly to an open position) to place food on the grill, to remove food from the grill, and to observe the cooking food. Since heated air rises relative to surrounding cooler air, each time the grill's lid is opened, essentially all of the heated air in the cooking chamber rises and escapes, requiring the chamber to heat up again after the lid is pivoted downwardly to close the grill's cooking chamber. Not only could this lengthen the time required to cook the food, but it could lead to uneven cooking since the air in the space beneath the food is likely to remain much hotter or at least heat up much more quickly than the air in the space above the food after each opening of the lid. This is particularly problematic with respect to cooking pizzas because the pizza dough and/or the solid surface on which the pizza must sit (such as a pizza stone) forms a large uninterrupted barrier between the air space below the pizza and the air space above the pizza. Also, since pizza recipes often require extremely high temperatures, temperature differentials can be significant.